At present, a radio network includes multiple radio access technologies (multi-RAT), such as, for example, a global system for mobile communication (GMS), a universal mobile telecommunications system (UMTS), long term evolution (LTE) and wireless fidelity (WIFI), etc. Since different services may need different RAT base stations to bear, when a multi-mode user equipment (UE) initiates a service, which RAT base station bears the service is an important problem.
Normally, there does not exist direct interface between different RAT base stations, so they could not directly interact resources, load and other information. Therefore, a centralized control entity (Controller) is introduced in the prior art to control the multiple RAT base stations, and an interface is present between the centralized control entity and each of the RAT base stations. The centralized control entity may receive information reported by each of the RAT base stations, such as load condition, position information of a user equipment and/or the like, and control the each of the RAT base station hereby. In a current LTE network, a single-card dual-standby solution is generally adopted for voice service and data service under multi-RAT. In the solution, when a user equipment is idle, the user equipment simultaneously resides in LTE and a second generation mobile network communication technology/third generation mobile network communication technology (2G/3G, 2nd Generation/3rd Generation) network, wherein the voice service is initiated via the 2G/3G network, and the data service is initiated via the LTE network. Since the user equipment needs to simultaneously reside in two networks, power consumption is increased. Therefore, a circuit switched fall back (CSFB) solution is further proposed in the prior art. In the solution, a user equipment resides in the LTE network when being idle, and when a user initiates a call or receives a call, the user equipment switches to the 2G/3G network and switches back to the LTE network after the call is terminated.
In a research and practice process of the prior art, the inventor of the present invention has found that, although the circuit switched fall back solution may reduce power consumption of a user equipment, the solution can only aim at voice service, and in the presence of voice service, the user equipment must switches to the 2G/3G network, while the 2G/3G network is not necessarily suitable for bearing the service at the moment, so a data transmission error may occur; and moreover, the solution can only falls from LTE back to the 2G/3G network, therefore, the solution has limitation and is not flexible enough.